The present application claims priority under 35 U.S.C. xc2xa7119 of German Patent Application No. 101 59 411.9 filed Dec. 4, 2001, the disclosure of which is expressly incorporated by reference herein in its entirety.
1. Field of the Invention
The invention relates to a device for dewatering a fibrous material web, in particular a paper or cardboard web by expelling water by gas pressure, with at least one pressure chamber limited radially by at least four rolls arranged in parallel and axially by sealing units. A pressure gas can be introduced into the pressure chamber, through which the fibrous material web can be guided.
2. Discussion of Background Information
Such a so-called xe2x80x9cBCP pressxe2x80x9d (Beck Cluster Press) is known, e.g., from German Patent Application No. DE A 199 46 971. Since this is a relatively new technology, there is still room for further optimization measures in its practical implementation.
The present invention provides a device of the type mentioned at the outset, which ensures the most reliable possible operation with the simplest possible structure.
The invention is directed to a device for dewatering a fibrous material web, e.g., a paper or cardboard web, by expelling water by gas pressure. The dewatering device of the instant invention includes at least one pressure chamber limited radially by at least four rolls arranged parallel to each other and limited axially by sealing units. Moreover, the rolls and sealing units can each be at least partially individually axially adjusted. A pressure gas can be introduced into the pressure chamber, through which the fibrous material web can be guided.
In accordance with the features of the instant invention, a cost-effective commercial manufacture of a reliably functioning BCP press is possible. The individual rolls and sealing units can expand individually according to the respective specific amount of heat and heat absorption and thus exhibit an individual behavior. The rolls and bearing units can now be adjusted, e.g., such that a resulting deviation in the overall length of the roll package is always as small as possible. Thus, an optimum lateral sealing of the pressure chamber is also always possible. Different heat expansions of the rolls and the sealing units can thus be compensated for at least considerably and an optimum, reliable method of operation of the press can be guaranteed.
In a preferred practical embodiment of the device according to the invention, the rolls can be axially adjusted by a control and/or regulating device such that a possible gap between the respective roll ends and the respective sealing unit is kept as small as possible.
Thus the rolls can be axially adjusted by the control and/or regulating device, e.g., such that a possible deviation of the overall length of the roll arrangement from a desired.length that can be preset is kept as small as possible.
It is therefore advantageous in particular for a zero adjustment of the rolls or a zero control or regulation to be conceivable.
In a preferred practical embodiment, the respective position of the rolls is determinable by position sensors, whereby the rolls can be axially adjusted accordingly by the control and/or regulating device depending on the position signals received. One position sensor each can be thereby assigned to the two ends or plugs of a respective roll.
Advantageously the rolls can be axially adjusted by the control and/or regulating device such that their axial centers always at least essentially lie in a common plane perpendicular to their axes.
The sealing units provided on both sides of the roll arrangement can preferably be controlled independently of one another and/or regulated individually.
The rolls can have at least partially a conventional structure which can compensate for sagging. For instance, a camber or a roll with an oil-supported, floating jacket circulating around a carrier is thus conceivable. In principle, however, the use of at least one shoe press unit or a shoe press roll is also possible. The rolls can thus be at least partially, e.g., arched, embodied as a sag compensation roll and/or formed by a shoe press roll.
In a preferred practical embodiment of the device according to the invention, one housing each is provided on both sides of the roll arrangement, in which housing the antifriction bearing units assigned to the relevant roll ends or plugs and the relevant sealing unit are contained. The antifriction bearing units can be mounted floating in the relevant housing. It is thereby possible, e.g., to support each of the bearing units in the relevant housing via a hydrostatic bearing unit.
Advantageously, the antifriction bearing units are identically constructed and each embodied as a fixed bearing.
Expediently, the rolls and/or the sealing units can be individually adjusted axially by the respective piston/cylinder units.
Preferably, each sealing unit is respectively provided with a flexible sealing arrangement. The sealing units can each comprise a seal having the shape of a dog""s bone.
The sealing units or sealing arrangements provided on both sides of the roll arrangement are preferably identically embodied, which results in a further reduction of the manufacturing costs.
The present invention is directed to a device for dewatering a fibrous material web by expelling water via gas pressure. The dewatering device includes at least four rolls arranged to radially limit at least one pressure chamber, and sealing units arranged to axially limit the at least one pressure chamber. Adjustment devices are arranged to at least partially individually axially adjust positions of the at least four rolls and the sealing units. A pressure gas is introducible into and the fibrous material web is guidable through the at least one pressure chamber.
In accordance with a feature of the present invention, the fibrous material web can be one of a paper or cardboard web.
According to another feature of the invention, the adjustment devices may include a control and/or regulating devices structured and arranged to axially adjust positions of the at least four rolls to maintain one of a seal and a small gap between the sealing units and respective ends of the at least four rolls.
According to still another feature of the instant invention, the adjustment devices can include comprise control and/or regulating devices structured and arranged to axially adjust positions of the at least four rolls to maintain a possible deviation of an overall length of a roll arrangement of the at least four rolls from a preset length to be as small as possible. The control and/or regulating devices can be arranged to provide a zero adjustment of the at least four rolls or a zero control or regulation.
In accordance with another aspect of the present invention, the adjustment devices may include control and/or regulating devices structured and arranged to axially adjust positions of the at least four rolls. The dewatering device can further include position sensors, arranged to determine respective positions of the at least four rolls, that are coupled to the control and/or regulating devices so that the axially adjustment of the positions of the at least four rolls is made in accordance with the position determinations by the position sensors. At least one position sensor can be assigned to each end of a respective roll. Further, at least one of the at least four rolls can include plugs located at the roll ends, and the at least one position sensor is assigned to each plug of the at least one roll. Further still, at least one position sensor may be assigned to each at least one of an end and a plug of the at least four rolls.
The adjustment devices can include a control and/or regulating devices structured and arranged to axially adjust positions of the at least four rolls to maintain axial centers of the at least four rolls in a common plane perpendicular to the roll axes.
Moreover, the adjustment devices can include a sealing unit positioner structured and arranged to at least one of individually control and individually regulate positions of the sealing units, which are located on both sides of a roll arrangement formed by the at least four rolls.
The at least four rolls can be structured to be at least partially arched, and may include at least one of sag compensation rolls and one of shoe press units and shoe press rolls.
Housings may be located on each side of a roll arrangement formed by the at least four rolls, and the housings can include antifriction bearing units assigned to one of roll ends and plugs of the at least four rolls and the sealing units. The antifriction bearing units may each be mounted floating in the housings. The antifriction bearing units can each be supported in the housings via hydrostatic bearing units. The antifriction bearing units may have identical structures that comprise fixed bearings.
In accordance with another feature of the present invention, the adjustment devices can include piston/cylinder units structured and arranged to axially adjust positions of at least one of the at least four rolls and the sealing units.
According to still another aspect of the invention, the sealing units can include seals having a dog""s bone shape.
Moreover, according to another feature of the invention, the sealing units can include flexible sealing arrangements.
The sealing units, which are provided on each side of a roll arrangement formed by the at least four rolls, may be embodied identically.
The sealing units can include first and second plates and elastic elements arranged to couple the first and second plates together for relative movement between the first and second plates. A face of the first plate is structured and arranged to face one of an end and a plug of the at least four rolls, and the first plate face is arranged to maintain one of sealing engagement and at least a small gap with the one of the end and the plug of the at least four rolls to provide an adequate seal for the pressure chamber. Further, the first plate face can include a groove and an O-ring located in the groove, and the O-ring can be arranged to one of contact and maintain the small gap with the one of the end and the plug of the at least four rolls.
In accordance with still another feature of the present invention, the at least four rolls and the sealing units can be structured to exhibit heat expansion characteristics, and the adjustment devices may be arranged to axially adjust positions of the at least four rolls and the sealing units to compensate for the heat expansion.
The present invention is directed to a process for dewatering a fibrous material web in an apparatus that includes at least four rolls arranged to radially limit at least one pressure chamber, sealing units arranged to axially limit the at least one pressure chamber, and adjustment devices coupled to the at least four rolls and the sealing units. The process includes introducing gas into the at least one pressure chamber, and axially adjusting the positions of at least one of the at least four rolls and the sealing units with the adjustment devices. In this manner, one of sealing contact is made and a small gap is formed between the sealing units and ends of the at least four rolls to provide maintain sufficient pressure in the pressure chamber. The process also includes passing the web through the at least one pressure chamber, such that water in the web is expelled by the gas pressure.
In accordance with a feature of the instant invention, the adjustment devices may include piston/cylinder devices coupled the at least four rolls and the sealing units, and the axial adjustment of the at least one of the at least four rolls and the sealing units can be effected by at least one of the piston/cylinder devices.
According to another feature of the invention, the sealing units can include first and second plates and elastic elements arranged to couple the first and second plates together, the axial adjustment of the at least one of the at least four rolls and the sealing units can effect relative movement between the first and second plates. The process can also include positioning a face of the first plate to face one of an end and a plug of the at least four rolls, and locating the first plate face to maintain one of sealing engagement and at least a small gap with the one of the end and the plug of the at least four rolls to provide an adequate seal for the pressure chamber. Moreover, the first plate face can include a groove and an O-ring located in the groove, and the process may also placing the O-ring to one of contact and maintain the small gap with the one of the end and the plug of the at least four rolls.
In accordance with still yet another feature of the present invention, the at least four rolls and the sealing units are structured to exhibit heat expansion characteristics, and the process may further include axially adjusting positions of the at least one of the at least four rolls and the sealing units to compensate for the heat expansion.
Other exemplary embodiments and advantages of the present invention may be ascertained by reviewing the present disclosure and the accompanying drawing.